Re: OT: Zone

Celia 

You have raised, or maybe I inadvertently raised, a very interesting and
complex question.  The impact of climate of animals and plants was a
major subject of study in the early part of this century and is
summarized in two books written in the 1950's -  "Animal Ecology to-day"
by Bodenheimer in Israel and "The Distribution and Abundance of Animals"
by Andrewartha and Birch in Australia.  Parellel work was also published
in botany.

In simple terms, these studies showed that animals live in areas where
the degree days (that is the accumulated degrees above freezing during
the year) reach the required level for reproduction, etc.  If the number
is 1000 the area can be cool and have a long season of hot and have a
short season.  Once you accumulate 1000 you cross the line and
reproduction occurs.  At the same time, there humidity barriers - above
and below - at which the same organisms will not reproduce.  The view of
these scientists was developed in very dry areas of the world where the
ecology is quite simple and the physical environment dominates.  The
ideas are generally accepted now and can be seen in the gradual movement
of first blooming slowly northwards from Louisiana right up to the
mountains of New Hampshire and Northern Alberta.  I would guess that
degree days (obtained from the local crop labs and probably available on
the internet now) would provide an excellent prediction of when you
plants will flower for each of us in our gardens each year.

The story is more complex, especially in more humid regions where other
organisms can play an important role.  We used to believe that fungi and
bacteria were important for successful propogation of some trees and the
members of the pea family. Now we discover that many (most) plants have
colonies of microfungi embedded in their roots and that these organisms
greatly influence the productivity of plants.  We are now planting crop
seeds with an innocculum of fungi.

Simple Conclusion - the physical environment determines the regions
where animals and plants can live and the microclimate and biological
environment in that region determines how well they do.  

Other factors are very important in some areas - for example, sunlight
at high altitudes on mountains and ultraviolet raidiation.  We are now
seeing quite a lot of damage and low productivity in crops such as
soybean (soyabean) caused by ultraviolet light and the decrease in the
ozone layer.  This is not a mild affect, the plants are seriously
sunburnt.

I may have confused you!  If you have specific questions, why not e-mail
me directly and I will try and help.

Ian
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